The present invention relates to wafers used for the selective connecting and disconnecting of plastic tubes such as would be used in total containment welding devices which have been described in various patents. The wafer is used in such systems as the component for heating the plastic tubes either as part of a process which disconnects a single tube into two tube sections for later welding of at least one tube section to the tube section of a different tube. When used for the connect process the wafer applies heat to separate tube ends causing the tube ends to melt so that the melted ends could be pressed together and form a unitary tube.
Frequently, the selective connecting and disconnecting of plastic tubes is performed in connection with medical techniques. Under certain circumstances it is necessary that the wafer be a single use wafer. The United States Food and Drug Administration, for example, has requirements prohibiting multiple use of devices such as wafers under certain conditions.
U.S. Pat. No. 5,525,186 discloses a particularly advantageous manner of assuring that a wafer would be used only once. As described in the '186 patent the wafer is provided with an aperture into which a sensing material is located. During the connect/disconnect operation the wafer moves past a sensor. When the sensor detects the presence of the sensing material in the aperture the process continues. If, however, no material is in the aperture, the absence of the material is sensed and the process is halted by deactivating the device. The particular sensing material disclosed in the '186 patent is a material which melts upon being heated. Thus, when a wafer is used for the first time the sensing material is initially in the aperture and detected by the sensor. Subsequently, when the wafer is heated the sensing material melts and there is no longer any material in the aperture. If an attempt is made to reuse the same wafer the sensor would detect the absence of the material or the open hole or aperture.